The extract exhibiting these beneficial properties is derived from the root and rhizome of Salvia miltiorrhiza Bunge, a perennial herb from the Labiatae family. In Traditional Chinese Medicine (TCM) it is also referred to as Danshen.
Danshen was recorded as a top-grade herbal medicine in Shennong's Classic of Materia Medica, as well as in Compendium of Materia Medica and Annotations to the Divine Husbandman's Classic of Materia Medica.
It has broad clinical applications.
In the medical monographs of Coverage of the Materia Medica, Compendium of Materia Medica and Renewal of Herbal, Danshen is said to evacuate puss with detoxication, a reference to its anti-bacterial and anti-inflammatory effects.
It should be noted that in TCM whole extracts, usually obtained as decoctions, are typically used in combination with a number of other herbs.
Modern scientific research on Danshen started in 1930's.
The chemical constituents of Danshen can be divided into two main categories of chemicals:                lipid-soluble, and        water-soluble.        
Earlier studies on “active” compounds of Danshen have mainly been concentrated on the lipid-soluble compounds, where around 40 compounds have been found so far. These can be further divided into two groups:                Tanshinones (o-quinone structure) and        Rosiglitazones (o-hydroxy rosiglitazone, paraquinoid structure).        
Most of the tanshinone compounds are diterpenes, of which they are mainly diterpene quinones.
Studies on Lipid-Soluble Chemicals
Over 40 different compounds have been identified, including, for example: tanshinone, cryptotanshinone, tanshinone IIA, tanshinone IIB, methyltanshinone, hydroyltanshinone IIA, isotanshinone I, isotanshinone II, isocryptotanshinone, miltirone, L-dihydrotanshinone I, neotanshinone A, B, C, and salviol.
The structures of a few of these compounds are illustrated below:

Antimicrobial and Anti-Inflammation Effects
The early research on the lipid soluble compounds of Danshen focused on its antimicrobial effects and a series of screens on anti-bacterial, anti-fungi and anti-tubercle bacillus were carried out by the Institute of Materia Medica, Chinese Academy of Medical Sciences. The screen results showed that the total tanshinones significantly inhibited Staphylococcus aureus and an inhibition zone still appeared on sensitive strain 209P at the low concentration (6.25 μg/per tablet) on filter paper disc. The test on 50 erythromycin-resistant Staphylococcus aureus isolates from the clinic also showed activity.
A test comparing the activity of tanshinone and 10 antibiotics has been carried out and the results showed that Staphylococcus aureus which was resistant to antibiotics was susceptible to tanshinone.
With filter paper disc, 5 out of 10 chemicals isolated from Danshen demonstrated anti-Staphylococcus aureus activity. These chemicals were:                Cryptotanshinone,        Dihydrotanshinone,        Hydroyltanshinone,        Tanshinone IIB, and        Methyltanshinone.        
Tanshinone IIA, tanshinone I, and neotanshinone A, B, and C did not show activity.
A study on the anti-microbial activity of tanshinone HA, and its correlation with the solvent selection, was carried out by ZHU Jiarong et al. When tanshinones were dissolved in chloroform tanshinone IIA did not demonstrate any anti-microbial activity but when it was dissolved in dimethylformamide (DMF) tanshinone IIA and IIB showed activity against:                Escherichia coli at the minimum inhibitory concentration (MIC) 50 or 25 μg/ml,        Staphylococcus aureus ATCC225923 with MIC 100 or 50 μg/ml,        Bacillus aeruginosus ATCC227853 with MIC 50 or 25 μg/ml, and        Haemolytic streptococcus with MIC 121.5 or 25 μg/ml.        
LUO Houwei et al reported tanshinone and 42 related compounds were tested against Tubercle bacillus in a structure-activity correlation study. It demonstrated that the quinone group was the principle structure responsible for the activity. 19 compounds with quinone group isolated from Danshen showed potent anti-bacterial activity and the MIC ranged between 0.31-5 mg/l. The bacteriostasis activity of o-quinone compounds was stronger than that of p-quinone compounds. A-ring hydroxylation or dehydrogenation of the inter ring resulted in less bacteriostasis activity. Different substitutions at a-H furan ring of tanshinone clearly affected bacteriostasis activity.
L I Jiangqin et al. reported the study on tanshinone IIA, cryptotanshinone and their zinc iron complex against Escherichia coli and Staphylococcus aureus activity. Compared with each other, cryptotanshinone was more potent than tanshinone IIA. Cryptotanshinone showed better inhibition effect against Staphylococcus aureus than Escherichia coli. The bacteriostasis activity was enhanced when cryptotanshinone complex was formed with metal ions, especially with zinc.
LUO Yongjian et al reported that a bacteriostasis experiment was carried out on a product called “Xiao Yan Kun” which was extracted from Gansu Danshen. The main compounds of the product were cryptotanshinone and tanshinone IIA. In the test, acetone was used as solvent and berberine and oxytetracycline were used as the positive controls. The bacterial stains included Staphylococcus aureus, Bacillus subtilis, Streptococcus agalactiae, Pseudomonas aeruginosa, Escherichia coli, and Streptococcus dysgalactiae, respectively. The test samples showed better activity against Staphylococcus aureus, Bacillus subtilis and Streptococcus agalactiae than that of berberine. Cryptotanshinone was more active than tanshinone IIA but both samples were less active than oxytetracycline. Both samples showed no effect on Pseudomonas aeruginosa, Escherichia coli and Streptococcus dysgalactiae. 
The patent literature makes reference to a number of Salviae extracts.
CN101073599 discloses an extract of total ketone of comprising cryptotanshinone, tanshinone I, tanshinone IIA, methyl tanshinon, dihyderotanshinon I and ramification for use as a medicine or food.
CN1927265 discloses a process for increasing cryptotanshinone content in Salviae miltoiorrhizae extract.
CN1670019 discloses a method for extracting tanshinone in which a first extraction gives cryptotanshinone and dihydrotanshinone and a second extraction gives tanshinone IIA and tanshinone I.
CN1944455 discloses a method of increasing the content of cryptotanshinone, dihydrotanshinone, tanshinone IIA and tanshinone I using column chromatography with a given simultaneous solvent extraction.
None of the above specifically disclose an extract as characterized by the claims of the present invention.
Additional prior art includes:
US2003/0031690 which discloses a cosmetic composition comprising cryptotanshinone which is said to inhibit 5 alpha reductase activation. KR20020028041 which discloses the use of a composition containing Salviae miltoiorrhizae extract to treat pimples based on it's inhibition of 5 alpha reductase.
CN1317308 which discloses a cryptotanoshine containing cream to treat acne.
Biosci Biotechnol. Biochem 63 (12) 2236-2239 suggests that superoxidase radical formation might be the cause of the antibacterial activity of cryptotanshinone, dihydrotanshinone I.
More recently, in the Journal of Microbiology, August 2007 p350-357 it has been reported that Salvia miltiorrhiza shows anti-microbial activity against MRSA. Different extracts were studied, including methanol, hexane, chloroform, ethyl acetate, butanol and water. The best activity was found in hexane and chloroform fractions. MIC for the hexane fraction against various MRSA specimens was 64<MIC's>128 μg/ml.
With drug resistance proving such a major problem today, any active medicines or bactericidal compositions would be highly desirable.
It is an aim of the present invention to provide a medicine or bactericidal compositions which is/are effective against MRSA in low doses and which can be produced effectively on a commercial, as opposed to laboratory scale.